AstraZeneca's Covid-19 vaccine should only be given to people aged between 18 and 64, Germany's vaccine committee said in a draft recommendation, a day ahead of a decision by European regulators on whether to approve the drugmaker's shot.

"There are currently insufficient data available to assess the vaccine efficacy from 65 years of age," the committee, also known as Stiko, said in a draft resolution made available by the German health ministry on Thursday.

"The AstraZeneca vaccine, unlike the mRNA vaccines, should only be offered to people aged 18-64 years at each stage," it added.

Stiko's assessment was based on the same trial data published by medical journal The Lancet on Dec 8.

The European Union approved a vaccine developed by Pfizer and its German partner BioNTech in late December, and gave the green light to a shot made by Moderna in early January.

AstraZeneca did not immediately respond to a request for comment.

On Monday, the drugmaker denied that its Covid-19 vaccine is not very effective for people over 65, after German media reports said officials fear the vaccine may not be approved in the European Union for use in the elderly.

The German health ministry said of the 341 people vaccinated in the group aged 65 and over, only one became infected with the coronavirus, meaning the expert vaccine panel had not been able to derive a statistically significant statement.

AstraZeneca Chief Executive Pascal Soriot said the company had less data than other drugmakers on the elderly because it started vaccinating older people later.

"But we have strong data showing very strong antibody production against the virus in the elderly, similar to what we see in younger people," he told Die Welt newspaper in an interview earlier this week.

Germany is grappling with limited vaccine doses after Pfizer and AstraZeneca announced delays to deliveries in recent weeks, and Health Minister Jens Spahn warned the shortage would last well into April.

Spahn said there were younger age groups with existing conditions who were waiting to be vaccinated, adding the final recommendation on the use of the AstraZeneca shot would only come following EU approval.

As well as those aged over 80 and people living in senior citizens' homes, Germany is prioritising front-line medical and care staff.

In late December, Britain became the first country to approve the coronavirus vaccine developed by Oxford University and AstraZeneca.

The government said it would not recommend one vaccine over another for different cohorts of the population, even though data on the AstraZeneca/Oxford shot's efficacy in older people is currently limited.

It began rolling out the vaccine in January in a campaign that has targeted older people and seen more than 7 million given their first dose. Britain has also been using the vaccine developed by Pfizer and BioNTech.